Nonferrous metal



Patented Nov. 17, 1936 UNITED STATES NONFERROUS METAL Henry Charles Anstey, Oheadle, ,Stoke-on-Trent,

and William Ernest Alkins, Leek, England, as-

signors to Thomas Bolton & Sons Limited, Widnes, England, a. companyof Great Britain No Drawing. Application November 8, 1934, Serial No. 752,184. In'Great Britain October 3 Claims. (01. 17 1 v This invention relates to improvements in zinc more than of silicon and not less than alloys and to articles made therefrom such. as

rolled sheets.

It is known to prepare binary alloys of zinc for special purposes. Moreover, good quality commercial brands of zinc, which contain lead, are commonly used for the manufacture of engraving sheets. It is known that zinc in its cast state has a crystalline structure which makes it diflicult to work and until such structure has been modified by heat treatment or other means, it is unsuitable for many industrial purposes. Further, zinc both in the pure state and also when mixed or alloyed with certain other elements such as lead can be rolled successfully only at temperatures not exceeding 200 C., and after rolling either hot or cold it undergoes serious increase of grain size when heated to temperatures of 250 to 300 C.

According to the present invention alloys of zinc are prepared which contain one or more metallic elements together with silicon in an amount not greater than is required to form a silicide; suitable metallic elements are nickel, coba t, manganese, copper, chromium, g esium, aluminium and iron. The proportion of the metallic element or elements is usually less than 5 per cent., and that of silicon considerably less than 5 per cent.; the ratio of silicon to the metallic element or elements must not exceed that corresponding to the chemical composition of the silicide or silicides of the particular element or elements, but may be considerably less than this amount.

The added metal is usually present in an amount below 3 per cent.

Of the metallic elements mentioned, nickel has been found to be especially suitable, and the application of the invention will be illustrated with particular reference to the use of nickel. The preferred content of nickel is between 0.10 and 0.60 per cent., and that of silicon correspondingly must not exceed 0.025 to 0.15 per cent., according to the nickel content used, i. e. about one-fourth of the content of nickel.

If magnesium is used separately or in conjunction with other metallic elements, the permissible proportion of magnesium is much less than in the case of nickel. Aluminium has the disadvantage that if present in large quantity engraving sheets made from the alloy are found to blacken in use.

A suitable method of incorporating the ingredients is as follows:

The nickel and silicon are first alloyed to contain a suitable proportion of silicon, that is, not

of nickel. After alloying this metal is subdivided by pouring in a thin stream into Water in the usual way. A proportion of this alloy is dissolved in molten zinc to make an alloy containing about 5% of nickel with a corresponding percentage of silicon. This rich alloy is used by adding to the molten zinc to give the proportion of nickel required in the casting, which is then ready for the hot rolling operation. Thus, if 101% of silicon is used, there is present at least 04% of nickel.

Alloys prepared according to the present invention possess very favourable qualities as compared with zinc itself or with the previously known alloys of zinc. Thus the new ternary a1- loys of zinc, nickel, and silicon cast Well; they are readily worked hot, from temperatures of 350 C. or even higher, and are capable of undergoing severe cold working. Cast ingots possess a small and even grain size, and the grain size after hot and/or cold working is not seriously increased by heating temperatures as high as 350 to 380 or even 400 C. The alloys possess both in the cast and in the worked state great ductility and a hardness which makes them suitable for many technical applications. As a result of these valuable properties the alloys are capable of being rolled direct from the cast ingots without preliminary heat-treatment, and at much higher temperatures than are customary with zinc or the usual alloys of zinc, and their high ductility enables them to be rolled into thin sheet strip or foil and to be drawn into Wire. In fact, the presence of a small proportion of a metal silicide greatly assists mechanical working of the zinc alloy, in general.

The alloys possess numerous technical applications and they are particularly suitable, for example, for the manufacture of engraving sheets. Such engraving sheets are characterized by exceptional cleanliness, uniformity, and rapidity of etching, while their immunity from any development of coarse grain structure at temperatures encountered during the burning-in process considerably simplifies the latter operation. Sheets for use in lithography afford another illustration of their successful application in the arts. The alloy is also particularly suitable for extruding into rods or rolling and drawing into wire.

The zinc employed in the preparation of these alloys may be electrolytic zinc or commercial zinc; in general the former is preferred. In addition to the elements already enumerated, that is in addition to one or more of the metallic elements previously named and to the corresponding proportion of silicon, the alloys may contain, if desired for special reasons, small amounts of other elements such as aluminum or cadmium. In the case of those alloys containing zinc, nickel, and silicon, the proportion of other metallic element or elements added should not exceed one-half that of the nickel present.

A typical alloy which may be prepared according to the present invention contains 0.16 to 0.18 per cent. of nickel and 0.01 to 0.03 per cent. of silicon. The alloying elements may be added to the molten zinc before casting, but it is preferable to prepare initially an alloy of zinc, nickel, and silicon which is relatively rich in nickel and silicon and then incorporate this. in the zinc. It has been found that the alloys are best prepared by melting in an electric induction furnace.

The function of the silicon appears to be twofold: it appears to effect complete deoxidation of the alloy and so to allow of the production of sound dense castings free from porosity and from oxide inclusions; it is further believed that the residual silicon may be present in the form of a metallic silicide such as NizSl or COzSi etc., and that it may exist in this combination as a disperse phase distributed throughout the mass of the alloy.

We declare that what we claim is:

1. A zinc alloy capable of hot working from temperatures in excess of 350 C. and capable of reheating thereto without substantial increase of grain size, containing substantially 0.10% to 0.60% of a metal selected from the group consisting of nickel and cobalt, 0.01% to 0.15% of silicon, and at least 97% of zinc.

2. A zinc alloy capable of hot Working from temperatures in excess of 350 C. and capable of reheating thereto without substantial increase of grain size, containing .16% to .18% of nickel, .01% to .03% of silicon, and the remainder zinc.

3. A zinc alloy capable of hot working from temperatures in excess of 350 C. and capable of reheating thereto without substantial increase of grain size, containing at least 97% of zinc, the remainder consisting of .01% to .15% of silicon and .10% to .60% of a metal selected from the group consisting of nickel and cobalt, the ratio of the metal to the silicon being always at least 4:1.

HENRY CHARLES ANSTEY. WILLIAM ERNEST ALKINS. 

